The present invention is directed to a fastening device for holding construction or functional elements such as door panel snap pins on cover plates such as interior door and side panels on automobiles. These plates or panels usually are made from molded fibers.
One type of existing fastening device includes a holding plate which is spaced above the cover plate or panel to receive the construction or functional part, and which has support plates connected to opposite sides thereof by side walls. The support plates engage the cover plate and include cramps or claws which are tabs bent downwardly from the support plates and which can be forced into the cover plates to secure the holding plate thereto.
Such a fastening device is shown in U.S. Pat. No. 4,424,612. There, the support plates on both sides of the holding plate are provided with two stamped out claws each of which is located as close to the side walls as possible, one behind the other. The holding strength of these claws depends upon the hardness of the material of the cover plate. Where a higher holding force is required, problems are encountered in providing further claws in the available space in the support plates.
While it is possible to make the support plates larger so that they can accommodate additional claws, this is often precluded because of lack of available space. Also, the claws which are farther away from the side walls contribute only slightly to the holding force because tensional forces acting on the holding plate tending to pull it away from the cover plate act mainly on those claws which are adjacent the side walls.